Selective deposition modeling is one form of solid freeform fabrication, also known as additive manufacturing, for forming three-dimensional objects from computer aided design (CAD) data or other data defining the object to be made. Selective deposition modeling, sometimes referred to as 3D printing, is generally described in prior art patents, that include, but are not limited to, U.S. Pat. Nos. 4,999,143; 5,501,824; 5,695,707; 6,133,355; 6,162,378; 6,193,923; and 6,270,335 that are assigned to the assignee of the present application and the disclosures of which are incorporated by reference herein in their entirety.
Selective deposition modeling often includes the depositing of a build material to form the object and a support material that supports the build material during the forming of the object. The support material is typically removed after the object has been formed. Because the support material and build material may have different chemical and/or mechanical properties, selective deposition modeling with both materials can lead to undesirable effects, such as undesired surface features on the object being formed or undesired separation of one material from an adjoining surface of a different material that may result in inaccuracies in the final object.
Some prior art solutions to problems created by the use of support material and build material include providing a third material, such as an interface material. One example of a prior art solution that includes a distinct interface material is provided by U.S. Pat. No. 7,364,686, the disclosure of which is incorporated by reference herein in its entirety. However, providing a third material adds complexity and cost to the selective deposition modeling device and processes.
Therefore it is desirable to provide methods and apparatus for forming three-dimensional objects that include minimal or no undesirable surface features resulting from the interfaces created between the build material and/or the support material with one another and/or with other surfaces or materials.